Chester Carlson used Pál Selényi's ideas

Carlson did chemical experiments in his own home, to the frustration of his family and neighbours. He mad smelly compounds, melting sulfur over zinc plates in the kitchen smelling like rotten eggs, and once even starting a fire.

Carlson used Selényi’s ideas (more or less to use light to remove static charge, not create it) and his own. After many experiments, he had a breakthrough and created the first copy in 1938.